docs: def lev_bounds(self):
          """Pressure levels at grid interfaces (hPa or mb)
  
          :getter:    Returns the bounds of axis ``'lev'`` if availible in the
                      process's domains.
          :type:      array
          :raises: :exc:`ValueError`
                      if no ``'lev'`` axis can be found.
  
          """
          try:
              for domname, dom in self.domains.items():
                  try:
                      thislev = dom.axes['lev'].bounds
                  except:
                      pass
              return thislev
          except:
              raise ValueError('Can\'t resolve a lev axis.')